As is known in the art, one type of conventional current sensor uses a magnetic field transducer (for example a Hall effect or magnetoresistive transducer) in proximity to a current conductor. The magnetic field transducer generates an output signal having a magnitude proportional to the magnetic field induced by a current that flows through the current conductor.
Some typical Hall effect current sensors include a gapped toroid magnetic flux concentrator, with the Hall effect element positioned in the toroid gap. The Hall effect device and toroid are assembled into a housing, which is mountable on a printed circuit board. In use, a separate current conductor, such as a wire, is passed through the center of the toroid. Such devices tend to be undesirably large, both in terms of height and circuit board area.
Other Hall effect current sensors include a Hall effect element mounted on a dielectric material, for example a circuit board. One such current sensor is described in a European Patent Application No. EP0867725. Still other Hall effect current sensors include a Hall effect element mounted on a substrate, for example a silicon substrate as described in a European Patent Application No. EP1111693.
Various parameters characterize the performance of current sensors, including sensitivity and linearity. Sensitivity is related to the magnitude of a change in output voltage from the Hall effect transducer in response to a sensed current. Linearity is related to the degree to which the output voltage from the Hall effect transducer varies in direct proportion to the sensed current.
The sensitivity of a current sensor is related to a variety of factors. One important factor is the flux concentration of the magnetic field generated in the vicinity of the current conductor and sensed by the Hall effect element. For this reason, some current sensors use a flux concentrator. Another important factor, in particular for a current sensor in which a flux concentrator is not used, is the physical separation between the Hall effect element and the current conductor.